Flat-bank crossbar switch



1 A. T. SIGO 2,909,613

' FLAT-BANK CROSSBAR SWITCH 2 Sheets-Sheet 2 Filed Nov. 30, 1954 FIG. 2

FIG 3 United States Patent FLAT-BANK CROSSBAR SWITCH Arthur T. Sigo, Maywood, 111., assign'or to International Telephone and Telegraph Corporation, New York, N.Y., a corporation of Maryland Application November 30, 1954, Serial No. 471,940

'5 Claims. (Cl. 179-2754) This invention relates to a flat-bank crossbar switch such as is used in automatic telephone systems and elsewhere. The principle object of the invention is to provide an improved flat-bank type crossbar switch which is of a simple, more reliable and more rigid construction.

The flat-bank crossbar switch is exemplified by the United States Patent No. 2,577,067, issued December 1951. In such a crossbar switch, the flexible contact members of the stacks used at the crosspoints extend parallel to the plane of the switch frame, rather than at right angles thereto, thus enabling the horizontal multiple, in addition to the vertical multiple, to be built in as a part of the bank construction. Heretofore, the frame of such a switch has been heavy and expensive when made reasonably rigid, since it has comprised heavy parallel bars connected by cross members which support the contact bank. Moreover, the construction of the hold armature, and of the selecting mechanism carried thereby for each vertical row of crossponts, has been complex and expensive to build and to adjust because, among other reasons, it has included rotatable select members which have had to be pivoted and guided on the hold armature.

According to the invention, the switch frame which supports the flat-type contact bank comprises a flat mounting plate, of relatively thin sheet material, having its side portions turned over and bent inwardly and secured together in a rigid box-like structure which does not require the separate side rails heretofore used. The actuating ladders of the crosspoint portions of the contact banks are conveniently shouldered against the flat mounting surface, with each ladder having a reduced actuating portion extending through the common mounting plate for selective actuation by its associated hold armature.

Further, according to the invention, any hold armature is'pivotally supported and confined by parts depending from the common mounting plate, and selection of any stackup is simply accomplished by moving one end of an armature-attached leaf spring member over an aperture in the armature.

The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent, and the invention itself will be best understood, by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings comprising Figs. 1 to 3, wherein:

Fig. 1 is a top view of a switch embodying the invention;

'Fig. 2 is a front view of the switch of Fig. 1; and

Fig. 3 is a sectional view, taken along line 3-3 of Fig.2.

Referring first to Fig. l, the improved crossbar switch shown therein includes an inverted box-like frame having a contact bank 150-secured thereto. The contact bank 150 may be constructed generally as is disclosed in the noted patent but having a thick insulator 153 located ice between its lower traveling blades and its mounting surface to prevent contact therewith. The stackup 150 is shown mounted on the flate plate portion 1 of the frame structure, having its front side 2 turned over and its rear side 3 turned over and bent inwardly to form flange '4. The ends 5 are bent over to provide the end members of the structure. The ends 5, are provided with inwardly extending flanges 6 to which the front and rear sides 2 and 3 are rigidly secured, as by welding. V

The plate 1 is provided with tapped openings 8 which receive screws 151 to secure the contact bank 150 thereto. Tapped openings 10 are provided to receive screws 114 (Fig. 2) which secure armature guide bracket 112 to the underside of 1. Suitable apertures 9 are provided to receive the reduced actuating portion of the ladders 152 of contact bank 150. As shown in Fig. 1, ladders 152 are normally shouldered against the top mounting surface. A

The inwardly extending flange portion 4, of rear side 3, serves as a mounting for bold magnets in the man ner as disclosed in the previously noted patent. The rear side portion 3 accordingly serves as a portion of the return pathfor the magnetic flux of the hold magnets 80.

Two left-L-shaped brackets 23 and two right-L-shaped brackets 24 rigidly .join, as by welding, the box-like structure to corner gussets 20 and 21. One portion of each gusset 20 and 21 is flanged inwardly to provide a mounting space for shaft brackets 18 and 19, see Fig. l. Shaft brackets 18 and 19 also serve as a mounting for select magnets M1 to M12, and its lower edge portion has suitable apertures for receiving the journaled armature end portions of the select shafts 81-2 to 811-12.

The shaft centering means and the method of mounting the crossbar switch within a switchboard structure may be as disclosed in the previously noted patent.

A pair of leg bails 11 underlie the frame structure. One of such leg bail 11 is shown in Figs. 2 and 3. As shown therein, the leg bail 11 is attached to the rear face of front side 2 by 'means of screws 12, and is attached to the flange portion 4 bymeans of screw 13. The bails serve as support legs during assembly, wiring, and adjustment of the switch.

The six select shafts 51-2, S3-4, 85-6, 87-8, 89-10, and $11-12, shown in Fig. l, are all of similar construction; aside view of shaft 81-2 being shown in Fig. 2.

. Each such shaft comprises a square rod, having its armature end journaled which is received in a suitable aperture in shaft bracket 18 or 19. The other end of the select shaft is cupped to receive the supporting spherical smooth end portion of an adjustable bearing screw 45. The body of screw 45 is threaded into its tapped opening in shaft bracket 18 with suflicient of the slotted head portion extending through the shaft bracket 18 to permit adjustment to insure minimum amount of friction and to compensate for any slight difference in shaft lengths occurring in construction. Screw 45 is provided with a locking nut 48 to lock the screw in a desired position. Armatures 51 are provided for the select shafts as shown in Figs. 2 and 3. Each comprises a plate-like main tractive portion, and an integrally-formed offset portion which is secured to the underside of the select shaft as by a rivet 54.

Armature 51 has a pair of winged portions 52 and 53 formed integrally therewith and arranged to be acted upon by the respective select magnets M1 and M2. The normal relationship between wings 52 and 53 of any shaft and the associated select magnets (such as M1 and M2) is illustrated in Fig. 3.

A shaft positioning assembly as disclosed in the noted patent is provided to return the selecting shafts S1-2, etc., to their normal (unoperated) position after the selective action of such shafts has been completed. I

A hold magnet 80 and armature 90 are provided for each vertical row of stackups to operate selected stackups of contacts therein.

As disclosed in the previously noted patent, the hold magnets 80 are adjustably mounted, as shown in Figs. 2 and 3, upon flanged portion 4, below and slightly to the left of their associated vertical row of stackups.

A hold-magnet armature 90 underlies each vertical row of stackups. Each is pivotally mounted near each end and in the center. A plan view of one such armature 90 is shown in Fig. 1, and side and front views are shown in Figs. 2 and 3.

Referring now particularly to Fig. 1, the armature 90 shown therein extends from rear side 3 to front side 2. It comprises three principal portions, formed integrally with each other, a tractive portion 91 which operatively overlies the upper end of the core of its corresponding hold magnet 80, a laterally extending (main) portion 92 which underlies the associated row of stackups, and a laterally extending (actuating) portion 97 having three connecting ann portions 96.

Main portion 92 has a downwardly extending flange 94 (Figs. 1 and 2) which serves to rigidify the armature.

Armature 90 is provided with three laterally displaced guide apertures 95 which receive offset portions 113 of the armature guide bracket 112 for pivotally securing the armature as will be hereinafter described.

A residual clip 99 is provided and is attached to the tractive portion 91 of armature 90 to eliminate any undesirable residual magnetism. The front stop of armature 90 is regulated by the longitudinal adjustment of the hold magnets 80, and the back stop is regulated as shown in Fig. 2 by an adjustable regulating back stop screw 119 which is threaded through the plate 1 of the frame structure for engagement with the tractive portion 91 of annature 90, and is secured in position after adjustment by lock nut 120.

Referring now particularly to Fig. 2, the armature guide bracket 112 is shown secured to the underside of plate 1 by screw 114 which threadedly engages plate 1. Angularly offset portion 113, of bracket 112 extends downwardly through apertures 95 of armature 90, and the armature is pivotally supported on pins 115, which are secured within suitable apertures in portion 113. The center guide aperture 95 (Fig. 1) has a reduced opening to receive portion 113, of the center bracket 112 to posi tion the armature.

Referring now particularly to Figs. 1 and 3, the actuating bar 97 is provided with twelve pairs of notches 100 and 101, one pair for each crosspoint (or stackup) Each notch 100 is in aligned relationship with the actuating ladder 152 of its respective stackup. Adjacent notch 101 serves as a clearance notch to receive the free end of its respective select loop 105.

Select loops 105 are generally U shaped being of thin spring material, such as Phosphor bronze. Each such loop 105 has an offset portion which is secured to the underside of bar 97 by means of clamping plate 108 and screws 109 (Fig. 3). The select loops are generally formed having a double-ended loop arrangement, except for the first and last select loops which are of a single loop form. The free end 107 of the select loops 105 passes upwardly through clearance notch 101 and is turned inwardly to terminate in a bridge portion 106. Loops 105 are normally tensioned that the free end portion 107 engages the edge of notch 101 to keep its bridge portion 106 in itsnorrnal unbridging position.

Referring particularly now to Fig. 3, a double-armed selecting lever 62 is provided for each pair of crosspoints and in its normal position occupies a position midway between and below a pair of crosspoints. Fig. 3, shows the relationship existing between such levers 62 and the select loop 105. Lever 62 is generally U-shaped being of suitable spring-sheet material having its mid-portion encircling three sides of the select shaft, such as shaft 81-2,

4 and secured thereto as by welding. Each upwardly extending arm 63, of lever 62 is ofiset inwardly near the select bar and terminates in offset portion 64 which engages portion 107 of spring 105.

Selection of the first horizontal row of stackups, for example, occurs responsive to the energization of the select magnet M1. The underlying wing 53 of the associated armature 51 is thereby attracted upwardly into engagement with magnet M1, whereby the first select shaft S12 is rotated in a counterclockwise direction as viewed" in Fig. 3. Thereupon, select levers 62 of shaft S1 2, one for each vertical row of stackups, are-tipped toward a position underlying horizontal row 1. In each idle vertical row of stackups (at which the hold armature 90 is in normal position), arm 63 of select lever 62, acts through portion 107, of loop 105, to move bridge portion 106 to an effective position below the ladder 152-of the first horizontal row. The first stackup is thereby selected in each idle vertical row in the switch.

Selecting shaft may be arranged torotate through a slightly larger angle than is required for bridge portion 106 to reach its effective position (with portion 107 engaging the edge of notch 101) to insure that all selecting levers rotate a suflicient amount. This excess shaft rotation is permitted by virtue of the inherent flexibility of 62 and 105.

Following the above described selecting action of the horizontal row 1 and while the concerned select magnet M1 is maintained energized, the hold magnet 80 associated with any idle vertical is energized. The tractive portion 91 of the hold armature 90 is thereupon attracted downwardly into engagement with the end of the core of magnet 80, rotating the armature structure about its axis to raise actuating bar 97 with all its select loops 105. Each actuating ladder 152 passes inelfectively through notches 100, except in the case of the selected stackup. There, the actuating ladder 152 of the selected stackup of the bank is raised by the overlying bridging portion 106 of select loop 105.

The hold magnet 80 of the concerned vertical row is maintained energized for so long a time as the connection established is to remain intact.

The energized select magnet (M1 in the assumed example) may be deenergized immediately following the operation of the hold armature 90. When this occurs, the concerned select shaft S1-2 acts to return to its normal position as described in the previously referred to patent.

Select loop 105 associated with the actuated contact remains in its bridged condition by virtue of the downward pressure of actuating ladder 152 against bridged portion 106. When the energized hold magnet 80 is sub sequently deenergized, the armature 90 therefore rotates back to its normal position by virtue of the weight of the actuating portion 97 and the select loop mechanism mounted thereon.

When portion 97 is lowered, the bridge portion 106 of select loop is released, whereupon spring 105 returns to its normal position having portion 107 engaging the other side of notch 101.

I claim:

1. A flat-bank crossbar switch comprising a generally rectangular frame in the general form of an open inverted box composed of a single piece of sheet material, which provides a main panel having a continuous flat external mounting surface and further provides two end panels extending angularly from the ends of the main panel and two side panels extending angularly from the sides of the main panel, the end panels joining the side panels along thevcorner lines of the structure, means for securing the side and end panels together along the said corner lines to give rigidity to the structure, a flat-type contact bank and means for securing it to the said flat continuous surface of the main panel, said bank including crosspoint stacks of contact members arranged in intersecting rows comprising rows extending along the main panel and rows extending across the main panel, select shafts and means fixed with the mounting frame for operatively supporting them below the said main panel in alignment with respective longitudinal rows of crosspoint stacks, hold bars and means fixed with the mounting frame for operatively supporting them between the main panel of the mounting frame and the select shafts in alignment with respective cross rows of crosspoint stacks, the said main panel having apertures therethrough underlying respective crosspoint stacks, and means for operating any crosspoint stack through its corresponding aperture under the joint control of its associated select shaft and its associated hold bar, the last said means including a separate portion for each crosspoint stack extending through its associated aperture.

2. In a flat-bank crossbar switch, a rectangular frame in the general form of an open inverted box with the top side of the inverted structure comprising a single flat sheet which provides a continuous flat upper mounting surface, means securing a flat-type contact bank to the said flat upper surface, said bank including crosspoint stacks of contact members arranged in intersecting longitudinal and cross rows, select shafts and means fixed with the mounting frame for operatively supporting them below the said flat sheet in alignment with respective longitudinal rows of crosspoint stacks, hold bars and means fixed with the mounting frame for operatively supporting them between the said fiat sheet and the select shafts in alignment with respective cross rows of crosspoint stacks, said flat sheet having apertures therethrough underlying respective crosspoint stacks, and means for operating any crosspoint stack through its corresponding aperture under the joint control of its associated select shaft and its associated hold bar, the said means for operating the crosspoint stacks including a separate depending actuating member for each said stack, each actuating member including a stop portion normally engaging a part fixed with the said fiat upper mounting surface, and including an actuating portion extending through the said corresponding aperture.

3. In a flat-bank crossbar switch, a rectangular frame in the general form of an open inverted box with the top side of the inverted structure comprising a single flat porting them between the said fiat sheet and the select shafts in alignment with respective cross rows of crosspoint stacks, said fiat sheet having apertures therethrough underlying respective crosspoint stacks, means for operating any cross point stack through its corresponding aperture under the joint control of its associated select shaft and its associated hold bar, each hold bar having longitudinally displaced guide apertures extending generally vertically therethrough to define a pivot axis for the hold bar, guide members for each hold bar fixed with and depending from the said flat sheet and passing through the guide apertures of the hold bar, and means fixed with the associated guide members for pivotally en gaging the underside of any hold bar to suspended it for movement about its said pivot axis.

4. A crossbar switch including a row of crosspoint stacks of contact members, with each stack of the row including a depending actuating member, a plate-like hold bar underlying and aligned with the row of actuating members and supported for an up and down movement to actuate and restore the contact members of any stack of the row by selective engagement with the actuating members, the hold bar containing clearance apertures underlying the actuating members respectively, each clearance aperture idly receiving its associated actuating member on the hold bar being moved up unless the aperture is bridged to cause the actuating member to be raised with the hold bar, means for selectively bridging the clearance apertures comprising bridging members closely overlying the upper surface of the hold bar near the clearance apertures respectively, spring members for the respective actuating members attached to and underlying the hold bar, the hold bar containing operating apertures through which the spring members extend to reach the upper surface of the hold bar, the said bridging means comprising horizontal extensions of the respective spring members, and select means for contacting the spring members selectively below the lower surface of the hold bar to cause the clearance apertures to be bridged selectively.

5. In a crossbar switch according to claim 4, wherein the said spring members are generally U-shaped, each said spring member having offset end portions, one ofiset end portion fixed with and depending from said hold bar, and the other offset end portion comprising said bridging means.

References Cited in the file of this patent UNITED STATES PATENTS 2,517,022 Peek Aug. 1, 1950 2,577,067 Arthur Dec. 4, 1951 2,718,559 Lundkvist et al Sept. 20, 1955 

